function [F] = func(x)
    if size(x, 1) == 1
        x = x';
    end
    % x0 = [0.54232, -0.321]';
    x0 = [-0.707027, -0.688818]';
    g = [sin(100*x(1)) - cos(100*x(2));  -cos(100*x(1)) + sin(100*x(2))];
    F = x(1:2) - ((1 - x(3)) * x0 + x(3) * g);
end
